1. Field of the Invention
The present invention relates to a technology where data stored in a first storage system is replicated in a second storage system.
2. Description of Related Art
In recent years, in order to offer a continuing service to customers at all times, a technology relating to remote replication has become important, so that a data processing system offers storage service even when a primary storage system experiences a failure. U.S. Pat. No. 5,170,480 to Mohan discloses a technology where information in the first information processing system is replicated in a second information processing system. In Mohan, a computer included in a first information processing system (hereinafter, “primary host”) coupled to a disk array device (hereinafter, “primary disk array device”) transmits data stored in the primary disk array device to a disk array device (hereinafter, “secondary disk array device”) included in a second information processing system through a communication line and a computer included in the secondary information processing system (hereinafter, “secondary host”).
On the other hand, due to development of computer networks, information processing systems owned by business enterprises become more complicated. As a result, the requirement for collective management of apparatuses connected to a network is increasing. As a technology satisfying such a demand, there has been devised a technology called virtualization where a plurality of storage subsystems connected with one another through a network, such as a Fibre Channel or the Internet, are managed collectively and are provided to the user as a virtually single or plural storage subsystems. Thereby, the user of the information processing system can use the plurality of storage subsystems as if it were a single storage subsystem.
As used herein, the term “storage subsystem” refers to the storage apparatus such as a hard disk drive, an aggregate of a plurality of hard disk drives, a disk array device wherein a control unit controls a plurality of hard disk drives, etc.
As used herein, the term “storage system” and “site” both refers to the system comprised of one or more host computers and one or more storage subsystems connected to them.
A host computer may be referred to as “host”.
A storage device may be referred to as “storage”.